Index: openacs-4/packages/acs-lang/tcl/lang-util-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-lang/tcl/lang-util-procs.tcl,v
diff -u -N -r1.54.2.5 -r1.54.2.6
--- openacs-4/packages/acs-lang/tcl/lang-util-procs.tcl	18 May 2020 21:20:20 -0000	1.54.2.5
+++ openacs-4/packages/acs-lang/tcl/lang-util-procs.tcl	17 Jun 2020 09:56:14 -0000	1.54.2.6
@@ -384,15 +384,23 @@
 
     @see lang::util::default_locale_from_lang
 } {
-    return [db_string default_locale_from_lang {
+    set locales [db_list locales_from_lang {
         select locale
         from ad_locales l
         where language = :language
           and enabled_p
           and (default_p or not exists (select 1 from ad_locales
                                          where language = :language
                                            and locale <> l.locale))
-    } -default ""]
+    }]
+    if {[llength $locales] > 1} {
+        ad_log error "multiple locales '$locales' defined for language '$language'. Change configuration on /acs-lang/admin"
+        set locales [lindex $locales 0]
+    }
+    #
+    # return 0 or 1 locale
+    #
+    return $locales
 }
 
 ad_proc -public lang::util::default_locale_from_lang {